CSI 410. Database Systems – Spring 2020Programming Assignment IThe total grade for this assignment is 100 points. The deadline for this assignment is 11:59PM, February 20, 2020. Submissions after this deadline will not be accepted. Students arerequired to enter the UAlbany Blackboard system and then upload a .zip file (in the form of [firstname] [last name].zip) that contains the Eclipse project directory and a short document describing:? any missing or incomplete elements of the code? any changes made to the original API? the amount of time spent for this assignment? suggestions or comments if anyIn this programming assignment, you need to implement a storage manager that maintains aseries of data objects in each data file. You first need to install and run Eclipse on your machineand import the “storage manager” project (see Appendix A). Please generate an API document(see Appendix B) and then take a look at that document as well as the source code to familiarizeyourself with this assignment. This assignment provides you with a set of incomplete classes (inparticular, see SlottedPage, FileManager, and BufferedFileManager which contain methodscurrently throwing an UnsupportedOperationException). You will need to write code for theseclasses. Your code will be graded by running a set of unit tests and then examining your code (seeSlottedPageTest and FileManagerTest which use JUnit1, as well as BufferedFileManagerTestwhich produces output messages). For details of running these tests, refer to Appendix A. Notethat passing unit tests does NOT necessarily guarantee that your implementation is correct andefficient. Please make sure that your code is correct and efficient so that it will not cause anyproblem in many other cases not covered by the unit tests. If you have questions, please contactthe TA(s) or the instructor. The remainder of this document describes the components that youneed to implement.Part 1. The Slotted Page Structure (50 points)The slotted page structure allows a storage manager to store variable-length records (dataobjects) within a fixed size page (an in-memory copy of a disk block). Each page is essentially abyte array that stores a header (at the beginning) and a number of data objects (at the end). Theheader of a page consists of (1) a 4-byte integer representing the number of entries in the page forstoring data objects, and (2) a series of 4-byte integers (one for each data object) each of whichrepresents where the corresponding data object is stored within the page (i.e., the location of thecorresponding data object within the page). Each page has, between its header and data objects,a free space where more data objects and header entries can be added. For further details of theslotted page structure, refer to Section 13.2.2 of the textbook. Upon a request to delete a dataobject from a page, the corresponding header entry (for storing the location of the data object)is simply set to -1 to indicate that there is no associated data object (the actual object is NOTnecessarily removed from the page).1http://junit.org1In this part, you need to implement the following methods (your code needs to pass all of the5 tests in SlottedPageTest):? add(Object o): adds the specified object o in the SlottedPage on which this method isinvoked. This method must first save the object o in the free space of the SlottedPage bycalling the save(Object o) method. This save(Object o) method returns an int valueindicating the location at which the object o is saved in the SlottedPage. That int valuemust be stored at the right header entry of the SlottedPage so that the saved object o canbe accessed in the future. For example, assume that object “123” is saved at location 2038 inthe byte array of an empty SlottedPage. Then, the first 4 bytes of the byte array (i.e., thebeginning of the header) must store an int value 1 to indicate that there is only one entry inthe header (in response to the addition of object “123”). The next 4 bytes of the byte array(i.e., the 0th entry in the header) must store 2038 (i.e., the location at which “123” is saved).When an additional object “456” is saved at location 2028 in the byte array, the first 4 bytesof the header must store 2 (to indicate that there are two entries in the header) and the 1stentry (i.e., the entry after the 0th entry) in the header must store 2028 (i.e., the location atwhich “456” is saved). To find the number of entries that the SlottedPage currently has, usethe entryCount() method. To set the number of entries in the header to an int value, usethe setEntryCount(int count) method. To save location l at the ith entry in the header,call saveLocation(i, l).? get(int index): returns the object at the specified index in the SlottedPage on which thismethod is invoked. For example, get(0) returns the object at index 0 (i.e., the object whoselocation is stored at the 0th entry in the header) and get(1) returns the object at index1. This method must first find the location of the object at the specified index by callingthe getLocation(int index) method. This getLocation(int index) method returns theint value stored at the header entry specified by index (i.e., the index-th header entry).If that location is -1, meaning that the object was removed from the SlottedPage, theget(int index) method needs to return null. Otherwise, get(int index) needs to obtainthe object by calling the toObject(byte[] b, int offset) method (with offset set tothe return value of getLocation(int index)) and then return that obtained object. If thegiven index cannot match any of the entries in the SlottedPage (e.g., get(-1)), the methodneeds to throw an IndexOutOfBoundsException.? remove(int index): removes the object at the specified index from the SlottedPage onwhich this method is invoked. This method must save -1 at the appropriate entry in theheader. This method must also return the object removed (i.e., the object previously storedat the specified index).? iterator(): returns an iterator over the objects (excluding those removed) stored in theSlottedPage on which this method is invoked. To find the number of entries in the currentSlottedPage, use entryCount(). To get the object at each index, call get(int index).Note that get(int index) returns null if there is currently no object at the specified indexdue to the deletion of the previous object. Feel free to add an auxiliary class or data structurefor this iterator() method.? compact(): reorganizes the SlottedPage on which the method is invoked (in ord代做CSI 410留學(xué)生作業(yè)、代寫Database Systems作業(yè)蔽挠、代做Java程序語言作業(yè) 幫做Haskell程序er to maximizethe free space of that SlottedPage). This method is used by the save(Object o)method when the object to save cannot fit into the current free space of the SlottedPage.This method needs to move objects at the end of the SlottedPage in a manner that eliminatesthe space previously wasted by the objects removed from the SlottedPage.2Please make sure that your code passes all of the tests in SlottedPageTest.Part 2. The Basic Storage Manager Implementation (40 points)In this part, you need to implement, in FileManager.java, a basic storage manager that maintainsa series of data objects in each data file without buffering (i.e., reading/writing SlottedPagesdirectly from/to data files). The methods to complete are as follows (your code needs to pass allof the 4 tests in FileManagerTest):? put(int fileID, Long location, Object o): puts object o at location location in thefile specified by fileID. Here, location has a long-type value, whose first half (4 bytescorresponding to an integer) represents the ID of the page (e.g., page 0, page 1, etc.) and thesecond half represents the index within the page. For example, put(10, 0x00000001L, o)stores object o in page 0 of the file specified by ID 10 (i.e., the first disk block in the file) atindex 1 within the page. On the other hand, put(10, 0x00010000L, o) stores object o inpage 1 of the file specified by ID 10 (i.e., the second disk block in the file) at index 0 withinthe page. Given a long-type argument location, use first(location) to get the ID of thepage and second(location) to get the index within the page. After finding an appropriatepage p, call put(int index, Object o) on p to put the object in that page and then callthe updated(p, fileID) method of FileManager to indicate that the page p is updated(then the updated(p, fileID) method of FileManager automatically writes the page tothe appropriate data file). If the location argument has an inappropriate value (e.g., its firsthalf refers to page -1), then put(int fileID, Long location, Object o) needs to throwan InvalidLocationException.? get(int fileID, Long location): returns the object at location location in the file specifiedby fileID.? remove(int fileID, Long location): removes the object at location location from thefile specified by fileID.? iterator(int fileID): returns an iterator over all objects stored in the the file specifiedby fileID. This method needs to use page(int fileID, int pageID) of FileManager anditerator() of SlottedPage. Make sure this method efficiently uses the memory (e.g., doesNOT put all of the objects in the memory first thereby incurring high space overhead andthen return an iterator over these objects).Please verify your code using the tests in FileManagerTest.3Part 3. Buffer Management (10 points)The FileManager class implemented in Part 2 directly accesses data files (i.e., no buffering),causing disk seeks frequently. In this part, you need to implement the BufferedFileManager classso that it extends the functionalities of FileManager in a manner that benefits from buffering(i.e., frequently used pages are kept in memory, thereby enabling fast read and write operations).Furthermore, you need to implement a page eviction policy for the cases where there are too manypages to keep in the main memory. The choice of eviction policy is up to you. It is not necessaryto do something sophisticated. Describe your policy in the document that you submit.When BufferedFileManager is implemented correctly, BufferedFileManagerTest will producesome output as follows (the exact number of reads and writes may vary depending on thebuffering strategy; however, there should in general be less reads and writes as the buffer sizeincreases):buffer size : 4 pages1000 additions % [ { name : table0 . dat , reads : 0 , writes : 3 8 } ]10 removals % [ { name : table0 . dat , reads : 1 0 , writes : 4 8 } ]iteration over 990 elements % [ { name : table0 . dat , reads : 5 2 , writes : 5 2 } ]shut down % [ { name : table0 . dat , reads : 5 2 , writes : 5 2 } ]buffer size : 16 pages1000 additions % [ { name : table0 . dat , reads : 0 , writes : 2 6 } ]10 removals % [ { name : table0 . dat , reads : 9 , writes : 3 5 } ]iteration over 990 elements % [ { name : table0 . dat , reads : 4 8 , writes : 5 1 } ]shut down % [ { name : table0 . dat , reads : 4 8 , writes : 5 1 } ]buffer size : 64 pages1000 additions % [ { name : table0 . dat , reads : 0 , writes : 0 } ]10 removals % [ { name : table0 . dat , reads : 0 , writes : 0 } ]iteration over 990 elements % [ { name : table0 . dat , reads : 0 , writes : 0 } ]shut down % [ { name : table0 . dat , reads : 0 , writes : 4 2 } ]Appendix A. Installing Eclipse and Importing a Java Project1. Visit:http://www.eclipse.org/downloads/2. From the web site, download the eclipse installer (those for Linux, Windows, and Mac OS Xare available) and then choose “Eclipse IDE for Java Developers” and install it.3. After finishing installation, start Eclipse.4. When Eclipse runs for the first time, it asks the user to choose the workspace location. Youmay use the default location.5. In the menu bar, choose “File” and then “Import”. Next, select “General” and “ExistingProjects into Workspace”. Then, click the “Browse” button and select the “storage manager.zip”file contained in this assignment package.6. Once the project is imported, you can choose one among SlottedPageTest.java, FileManagerTest.java,and BufferedFileManagerTest.java in the storage.test package and then run it by clickingthe icon highlighted in Figure 1.4Figure 1: EclipseAppendix B. Creating API documents using javadocOne nice feature of Java is its support for “documentation comments”, or “javadoc” comments,which you can use to automatically produce documentation for your code. Javadoc comments startwith “/**”. Inside a javadoc comment, there are some special symbols, like @param and @return.You can create HTML-based API documents from the source as follows:1. Click the “storage manager” project icon in the Navigator or Project Explorer window.2. Select “Generate Javadoc” from the “Project” menu.3. In the “Generate Javadoc” dialog box, press the “Finish” button.As it runs, it tells you that it’s generating various things. When it is finished, a few new foldersshould appear in your project: doc, doc.javadoc, and doc.resources. See what got generated (toopen the newly created HTML documentation files in a web browser window, just double-clickthem; you can start with “index.html”).5轉(zhuǎn)自：http://www.6daixie.com/contents/9/4920.html